Selective sequential recovery of zinc and copper from acid mine drainage

The observed imbalance between the unsustainable consumption of available natural metal resources and finite deposits makes the recovery and recycling of metals from metal-containing wastes an imperative. Here, ionic-liquid-based aqueous biphasic systems (IL-based ABSs) are proposed as an efficient alternative for selective metal recovery from real copper acid mine drainage (AMD) effluents. ABSs composed of different ILs and Na2SO4 were evaluated for Zn, Al, Cu, Co, and Ni extraction from both model solutions and AMD samples. It is shown that IL composed of thiocyanate anion ([SCN]−) presented a remarkable ability to extract metals from AMD through the formation of stable metal complexes. The addition of NaSCN to ABSs composed of tetrabutylammonium chloride ([N4444]Cl) allowed to mimic the use of [SCN]-based IL with additional advantages: tunable metal selectivity by the concentration of [SCN]− added to the ABS and a reduction in system cost and environmental impact. Furthermore, at the [SCN]− concentration range studied here, the formation of a hydrophobic salt composed of IL cations and metal complex anions is observed, which allows the selective extraction and recovery of transition metals in a single step. The IL-rich phase recyclability in three extraction cycles is demonstrated, showing the possibility to recover two times more Zn than with a single extraction cycle while using the same amount of IL and thiocyanate. Salt-rich phases were also recycled in a new IL-based ABS for the subsequent Cu extraction and recovery. These results allow the development of a sustainable process for the selective sequential recovery of transition metals from AMD.publishe

Environmental Risk Assessment Based on High-Resolution Spatial Maps of Potentially Toxic Elements Sampled on Stream Sediments of Santiago, Cape Verde

Geochemical mapping is the base knowledge to identify the regions of the planet with critical contents of potentially toxic elements from either natural or anthropogenic sources. Sediments, soils and waters are the vehicles which link the inorganic environment to life through the supply of essential macro and micro nutrients. The chemical composition of surface geological materials may cause metabolic changes which may favor the occurrence of endemic diseases in humans. In order to better understand the relationships between environmental geochemistry and public health, we present environmental risk maps of some harmful elements (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in the stream sediments of Santiago, Cape Verde, identifying the potentially harmful areas in this island. The Estimated Background Values (EBV) of Cd, Co, Cr, Ni and V were found to be above the Canadian guidelines for any type of use of stream sediments and also above the target values of the Dutch and United States guidelines. The Probably Effect Concentrations (PEC), above which harmful effects are likely in sediment dwelling organisms, were found for Cr and Ni. Some associations between the geological formations of the island and the composition of stream sediments were identified and confirmed by descriptive statistics and by Principal Component Analysis (PCA). The EBV spatial distribution of the metals and the results of PCA allowed us to establish relationships between the EBV maps and the geological formations. The first two PCA modes indicate that heavy metals in Santiago stream sediments are mainly originated from weathering of underlying bedrocks. The first metal association (Co, V, Cr, and Mn; first PCA mode) consists of elements enriched in basic rocks and compatible elements. The second association of variables (Zn and Cd as opposed to Ni; second PCA mode) appears to be strongly controlled by the composition of alkaline volcanic rocks and pyroclastic rocks. So, the second PCA mode is also considered as a natural lithogenic mode. The third association (Cu and Pb; third PCA mode) consists of elements of anthropogenic origin

Book of abstracts of the 27th Colloquium of African Geology: 17th Conference of the Geological Society of Africa

On behalf of the Local Organizing Committee of “27th Colloquium of African Geology/17th Conference of the Geological Society of Africa – CAG27”, we would like to welcome you to this important meeting regarding “Africa: The key player for a better and sustainable world” that we feel privileged to host. This Conference, sponsored by the Universidade de Aveiro and the GeoBioTec Research Centre, under the auspices of the Geological Society of Africa (GSAf), is an opportunity to continue the scientific exchanges between researchers from all over the world in the field of Geosciences, and to demonstrate the high scientific research standards that are being carried out over the world. The participants in the conference will have the opportunity to share their expertise in a range of scientific fields, such as geology, geological resources, environmental risks, environment and human health, sustainable development, education, and tourism in Africa. (...)publishe

Multivariate analysis for assessing sources, and potential risks of polycyclic aromatic hydrocarbons in Lisbon urban soils

Urban soils quality may be severely affected by polycyclic aromatic hydrocarbons (PAHs) contamination, as is the case of Lisbon (Portugal). However, to conduct a risk assessment analysis in an urban area can be a very difficult task due to the patchy nature and heterogeneity of these soils. Thus, the present study aims to provide an example on how to perform the first tier of a risk assessment plan in the case of urban soils using a simpler, cost effective, and reliable framework. Thus, a study was conducted in Lisbon to assess the levels of PAH, their potential risks to the environment and human health, and to identify their major sources. Source apportionment was performed by studying PAHs profiles, their relationship with potentially toxic elements, and general characteristics of soil using multivariate statistical methods. Results showed that geostatistical tools are useful for evaluating the spatial distribution and major inputs of PAHs in urban soils, as well as to identify areas of potential concern, showing their usefulness in risk assessment analysis and urban planning. Particularly, the prediction maps obtained allowed for a clear identification of areas with the highest levels of PAHs (close to the airport and in the city center). The high concentrations found in soils from the city center should be a result of long-term accumulation due to diffuse pollution mostly from traffic (through atmospheric emissions, tire debris and fuel exhaust, as well as pavement debris). Indeed, most of the sites sampled in the city center were historical gardens and parks. The calculation of potential risks based on different models showed that there is a high discrepancy among guidelines, and that risks will be extremely associated with the endpoint or parameters used in the different models. Nevertheless, this initial approach based on total levels was useful for identifying areas where a more detailed risk assessment is needed (close to the airport and in the city center). Therefore, the use of prediction maps can be very useful for urban planning, for example, by crossing information obtained with land uses, it is possible to define the most problematic areas (e.g., playgrounds and schools).This research was funded by FCT (Foundation for Science and Technology), through an individual research grant attributed to A. Cachada (SFRH/BPD/100429/2014), and through the research project URBSOIL-LISBON (PTDC/CTE-GEX/68523/2006). This work was also supported by the Strategic Funding UID/Multi/04423/2013 (CIIMAR), UID/GEO/04035/2013 (GEOBIOTEC), and UID/AMB/50017/2013 (CESAM RU), through national funds provided by FCT (Foundation for Science and Technology), and the European Regional Development Fund (ERDF), in the framework of the PT2020 Partnership Agreement

Produtividade do setor agrícola brasileiro (1991-2003): uma análise espacial

Agricultural productivity is characterized by location patterns, represented by the so-called spatial effects, namely, spatial heterogeneity and spatial dependence. This paper analyzes the spatial effects which exert influence on agricultural land productivity at three points in time – 1991, 1997 and 2003 – at the microregional level, using exploratory spatial data analysis (ESDA). The main finding shows that agricultural productivity is increasingly self-correlated in space, over time. Two high-high (HH) clusters are identified consistently: one of them is located in the State of São Paulo and parts of the Center-West region, while the other cluster (HH) lies in the Northeastern Coast.A produtividade agrícola é marcada por padrões de localização representados pelos chamados efeitos espaciais, a saber: a heterogeneidade espacial e a dependência espacial. Assim, este trabalho analisa os efeitos espaciais que exercem influência sobre a produtividade agrícola da terra para três momentos do tempo – 1991, 1997 e 2003 – em nível microrregional. Para isso, implementa-se a análise exploratória de dados espaciais. O principal resultado mostra que a produtividade agrícola está crescentemente autocorrelacionada no espaço ao longo do tempo. Dois clusters alto-alto (AA) são identificados consistentemente: um deles localiza-se no Estado de São Paulo e partes do Centro-Oeste, enquanto o outro cluster AA situa-se no litoral nordestino

Dual target strategy: a proposal to mitigate the risk of overtreatment and enhance patient satisfaction in rheumatoid arthritis

Commentary - abstract not available